Understanding　the　pharmacokinetics　of　prodrugs　in　vivo　necessitates　quantitative,　noninvasive,　and　real-time　monitoring　of　drug　release,　despite　its　difficulty.　Ratiometric　photoacoustic　(PA)　imaging,　a　promising　deep　tissue　imaging　technology　with　a　unique　capacity　for　self-calibration,　can　aid　in　solving　this　problem.　Here,　for　the　first　time,　a　methylamino-substituted　Aza-BODIPY　(BDP-N)　and　the　chemotherapeutic　drug　camptothecin　(CPT)　are　joined　via　a　disulfide　chain　to　produce　the　molecular　theranostic　prodrug　(BSC)　for　real-time　tumor　mapping　and　quantitative　visualization　of　intratumoral　drug　release　using　ratiometric　PA　imaging.　Intact　BSC　has　an　extremely　low　toxicity,　with　a　maximum　absorption　at　∼720　nm;　however,　endogenous　glutathione　(GSH),　which　is　overexpressed　in　tumors,　will　cleave　the　disulfide　bond　and　liberate　CPT　(with　full　toxicity)　and　BDP-N.　This　is　accompanied　by　a　significant　redshift　in　absorption　at　∼800　nm,　resulting　in　the　PA800/PA720　ratio.　In　vitro,　a　linear　relationship　is　successfully　established　between　PA800/PA720　values　and　CPT　release　rates,　and　subsequent　experiments　demonstrate　that　this　relationship　can　also　be　applied　to　the　quantitative　detection　of　intratumoral　CPT　release　in　vivo.　Notably,　the　novel　ratiometric　strategy　eliminates　nonresponsive　interference　and　amplifies　the　multiples　of　the　signal　response　to　significantly　improve　the　imaging　contrast　and　detection　precision.　Therefore,　this　research　offers　a　viable　alternative　for　the　design　of　molecular　theranostic　agents　for　the　clinical　diagnosis　and　treatment　of　tumors.　©　2023　American　Chemical　Society.